Just a guess, but your error message indicates that WordPress is using jQuery 1.4.4. If you look at the jQuery Mobile website, they’re using 1.5. Have you tried using wp_enqueue_script to use a jQuery 1.5? You’d want to try something like:
<?php
function my_init_method() {
if (!is_admin()) {
wp_deregister_script( 'jquery' );
wp_register_script( 'jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js');
wp_enqueue_script( 'jquery' );
}
}
add_action('init', 'my_init_method');
?>